What is the BLEND file format?
The .blend extension is used by 3D project files and animations created with the 3D modeling and rendering tool Blender. .blend files contain all elements of a project, such as objects, textures, NURBS surfaces, 3D mesh data, sounds, lighting information, animation keyframes, UV mapping layouts, and interface settings. A single .blend file can contain multiple scenes.
Main project file
.blend is the default file format used by Blender, developed and maintained by the Blender Foundation. A .blend file stores complete project data in a single, all-in-one binary container - no external dependency files are required unless assets are deliberately linked rather than packed.
Internally, .blend uses a block-based DNA/RNA structure, where an embedded DNA dictionary describes the exact C-struct layout used to write the file. This allows older and newer Blender versions to read each other's data with reasonable compatibility. Every .blend begins with the 7-byte ASCII signature BLENDER, followed by flags for pointer size and byte order, then a 3-digit version number.
By default, Blender also saves automatic backups as .blend1 and .blend2 alongside the main file. Projects can reference assets from other .blend files through Blender's library-linking system, keeping large pipelines modular. For exchange with other applications, scenes can be exported to formats such as .FBX, .glTF, or .DAE.
Security & safety
RISK: MEDIUMA .blend is data, but it is NOT purely passive: Blender files can embed Python scripts that run automatically (drivers, the "Register" / auto-run option, add-on hooks). Opening a .blend from an untrusted source with "Auto Run Python Scripts" enabled can execute arbitrary code. Blender disables auto-run by default and warns you - keep that off for files from strangers, and inspect/trust scripts only from known sources. Otherwise the geometry/material data itself is harmless.
Format details
in a nutshellPrograms that open BLEND files
Windows1 app
Blender
Open-source File > Open the .blend (or just drag it onto the Blender window). The only app that opens it fully. 
macOS1 app
Linux1 app
Blender
Open-source File > Open the .blend; available in most distro repos, as Flatpak/Snap, or from blender.org. 
Blender (no true web version)
Open-source There is no official browser-based .blend editor; download Blender. (Online 'viewers' usually require you to export to glTF first.) Technical details
deep spec| Magic bytes | 7 ASCII bytes "BLENDER" at offset 0 (hex: 42 4C 45 4E 44 45 52) |
| Pointer-size flag | Single byte at offset 7: "_" = 32-bit pointers, "-" = 64-bit pointers |
| Endianness flag | Single byte at offset 8: "v" = little-endian, "V" = big-endian |
| Version encoding | 3 ASCII digits at offsets 9-11 embed the Blender version (e.g., "404" = Blender 4.0.4) |
| Compression | Files are optionally gzip-compressed on save; compressed files start with bytes 0x1F 0x8B instead of the "BLENDER" header |
| MIME type | application/x-blender |
| Internal architecture | Block-based DNA/RNA binary database; an embedded DNA dictionary mirrors the C-struct layout used to write the file, enabling forward and backward compatibility |
| Multi-scene support | A single file can store multiple independent scenes |
| Asset packing | Images, sounds, fonts, and other external assets can be embedded ("packed") directly into the file to create a fully self-contained archive |
| Library linking | External `.blend` files can be linked (referenced without copying) or appended (data copied in), supporting large modular production pipelines |
| Backup naming | Blender automatically writes `.blend1` and `.blend2` backup copies alongside the main file on each save |
| Python data storage | Custom Python scripts, driver expressions, and add-on settings can be embedded and executed from within the file |
| Node graph storage | Shader, compositor, and geometry node trees are serialized as part of the scene data blocks |
| Cross-platform reading | Pointer-size and endianness flags allow `.blend` files authored on any platform to be read on 32-bit/64-bit and big/little-endian systems |
| Released | 1994 (Blender); .blend DNA/RNA structure stabilized late 1990s |
| Specification | docs.blender.org |
BLEND conversions
Community Q&A
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